Is it that if it dies it still returns to my hand? If so, how do I avoid that?

Is the UEOT clause nessesary for the haste?

I believe if it goes to the graveyard (or is exiled, or moved to another zone and then back onto the battlefield) it will not count as the same card, and the "return to hand" will not apply.

I'm not sure about "until end of turn". It's obviously almost always irrelevant whether it has haste is forever or not. I think conceptually it is more accurate with the restriction -- in principle, I think someone could stifle the "return to hand" ability, and then later someone else could gain control of it, and it would make a difference whether it could attack that turn. But this is never actually going to happen, and it's much easier to parse without.

For comparison, the suspend comprehensive rules (iirc) say a creature being unsuspended gains haste as long as you control it, but the reminder text just says "...without paying its mana cost. It has haste" which is totally correct but not complete. In other words, it does exactly what everyone expects, but the rules spell this out in full. Probably the same balance is correct here.

Alternatively, you could say "it can attack as though it has haste" but it's probably better to use the real keyword (in case any cards ever say "creatures with haste get blah")

PS. I do like the mechanic.

Thank you very much, both comments. I like to keep options open,so I will keep the clause. I also plan to use this with tap abiltys as well, so yeh, I will probably stick with the keword.

At the moment, if it dies, it won't come back to your hand, which I think is what you want.

Good, I actually don't want it it to come back. Thanks though.